Control mechanism for hoisting apparatus



S. ARNOLD, 3D.

CONTROL MECHANISM FOR HOISTING APPARATUS.

' APPLICATION FILED APR. 6, 1921.

1 A25, 5 69. Patented Aug, 15, 1922,

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S. ARNOLD, 3D. CONTROL MECHANISM FOR HOISTING APPARATUS. APPLICATION FILED APR. 6, I92I. 1 ;25 :569 Patented Aug, 1:), P322.

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SAMUEL ARNOLD, 3-D, F BEN AVON, PENNSYLVANIA.

CONTROL MECHANISM FOR HOISTING AEPARAT US.

Application filed April 6, 1921. Serial No. 458,923.

To all whom it may concem:

Be it known that I, SAMUEL ARNOLD, 3d, a citizen of the United States, and resident of Ben Avon, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Control Mechanisms for Hoisting Apparatus, of which the following is a specification.

This invention relates to hoists and more particularly to mechanism for'controlling the upward travel of the hoisting apparatus, and while not limited thereto, is particularly adapted to a motor driven highspeed crane or bucket hoist, and has for its object the provision of control mechanism adapted to be operated by the moving load to make and break the circuit to said motor bymeans of a limited switch.

Another object is to provide a mechanism of this class that will permit over-travel. of" the load after the control apparatus has-been tripped and the circuit broken to the driving mechanism. v

A further object is to provide a control apparatus of this type that will automatically reset the limit switch when the load is lowered.

A still further object is to provide a control mechanism that will not interfere with the usual lifting cables and other moving parts of the hoists.

The above and other objects will be more fully brought out in the following specification and illustrated in the accompanying drawings, in which I Figure 1 is a side elevation of a hoist trolley having my invention applied thereto.

Figure 2 is a sectional and elevation of the trolley on-the line II-II of Figure 1.

Figure 3 is a somewhat diagrammatic sectional side elevation of the limit switch for controlling the lifting mechanism of the hoist. I 1 i Figure 4 is a partial side elevation illus-.

trating the manner in which the. flexible op-.

erating cable. retrained over the several pulleys at the left-hand end of Figure-1, several parts being omitted and broken away for clearness.

Figure 5 is a cross sectional view on the line V-V-of Figure 1. V

Figure 6 is a typical wiring diagram for hoisting apparatus of the class to which my invention "belongs and shows my invention embodied therein.

1 sheave.

the path of travel Referring particularly to the drawings, the numeral 2 designates the hoist or crane trolley which carries the usual drums 3 and 4 operated by electric motors 5 and 6, respectively. The drums 3 and 4 carry the usual hoisting and closing ropes 7 and l -which are operatively connected to the bucket or other load device 7 in the usual manner.

The above apparatus will not. be described further in detail since it is not a part of this invention.

In carrying out my invention, 1 mount a rotary limit switch 10 on the trolley 2 to control the circuit to the motors 5 and 6.

The switch -10' is of usual construction having a drum 11 mounted on shaft 12 and having contacts 13 and 14. A sheave wheel 15 is mounted on one end of the shaft 12 for rotating the drum 11. y

A cable 16 is secured adj acent its one end to the sheave 15, so that a short length is on longer length is on the other side of said The short length of the cablelfi extends within a casing 17 and is provided with a counterweight 18 which normally pulls said sheave wheel 15 around, so as to close the limit switch 10 and when in this position the weight 18 rests upon the bottom of the casing .17.

The long length of the cable 16 is trained from the sheave-wheel 15 downwardly over a sheave 20, journaled in a'bracket 20*, on the bottom of the trolley 2, thence downwardly over a sheave 21' journaled in a bracket 22 which extends downwardly a considerabledistance below the'trolley to .the one side of the-path of travel of the load carrying. device 7. A second bracket 23 of equal length to'the bracket 22 extends downwardly from the trolley 2.011 the opposite side of of the load device 7 and has a sheave 2 journaled therein. The cable '16 is trained from the-sheave 21 across the path of. travel of'the loadv device 7 and, over the sheave Mthence upwardly over a one side of said sheave and a considerably til sheave 25 journaledin a bracket 26 on the bottom of the trolley 2, thence downwardly, into acasing 27 around a pulley 28 secured to a counterweight" 29,,wh'ich is normally supported on the bottom of the casing-.27. From theipulley '28 the cable is trained u'pwardly and-over a sheave 3O journaled in the bracket 26 and then downwardly and is secured to'the pulley 28.

' the a forward or liftlng circuit to the motors 5 and 6.

The load device or bucket 7 provided with van arched fender or plate 31 on its upper surface adapted to engage the stretch of cablebetween sheaves 21 and 24.

' In Figure 6 I have shown a wiring diagram of the ordinary control circuits used for apparatus of this class and having my limit switch incorporated therein. In'this diagramthe letters A and B designate the positive and negative line wires, respectively, which connect through a line switch 32 with.wires 33 and 34' When itis desired to raise the bucket 7 the controller 35 will he -moved to bridge contacts 36 and 37,

thus making a circuit from the positive wire 33 through the bridged contr' ler contacts 37, through wire 37, through contacts 38 of the limit switch 10,- through wire 39 to wire 40, then through the, armatures of motors 5 and 6, to wire 41, and to wire 42 to the contacts 43 of the limit switch 10.

-From the contacts 43 the current flows through wire 44 to the bridged'contacts 36 of the controller, to wire 34 and negative side ofxline through switch 32, thus completing the forward or raising circuit to the motors 5' and 6.

When the load device or bucket 7 reaches the predetermined upper position the limit switch 10 will be automatically tripped or opened, thus breaking the circuit through the contacts 38 and 43 of the switch and opening both sides of the line carrying the fOIWaId or raising circuit to the motors 5 an 6. 1' I After the switch 10 has been tripped and opened the controller 35 'will be moved to bridge contacts 45 and 46'of the controller and unbridge the contacts 36and '37 and a reverse circuit will then be made from the positive wire 33. to wire-47, throu h the bridged controller contacts 46 to wire 48,

to wire 41 to the armatures of theinotor's 5' and 6, through the armatures of the motors towire 40, towire 49, to brid edcontroller contacts 45 to wire 50 and t en to the negative wire 34and ne ative side of line through line switch 32, t us reversing;

the motors 5 and 6 to lower thebucket.

When the bucket or load device 7 reaches the lower position shown in dotted lines and cuit is broken the load device 7 will over travel, according to the speed at which it is traveling, the inertia of moving parts, and the braking applied until it reaches approximately the point indicated by position 0, the counterweight 29 being lifted while the load device 7 is moving upwardly from position b, to position 0.

After the switch 10 operates to open or break the forward or lifting circuit to the motors 5 and 6, this circuit cannot be again made until after the controller 35 has been thrown to the reverse, and the reverse circuit has been made to the motors to operate them in the reverse direction, which operation will lower the load device 7 and allow the ,switch 10 to automatically set itself again. However, the reset-ting of the switch 10 will not effect the operation of the motors 5 and 6, since when the controller 35 is reversed'to make the reverse circuit to the motors the 'contacts36 and 37 are unbridged and, therefore, the-forward or lifting circuit is broken at the controller.

When the load device or bucket 7 is be'- ing lowered the counterweight 29 will be the first to be seated in its normal position. Then counterweight 18 will exert its power on the cable 16 and pull around sheave 15 so as to rotate the drum of the switch 10 and reset said switch. 1

It will be ex ressly understood that the usual crane hook bucket 7, or other load devices may beused.

While I have shown and described one particular embodiment of my invention, I

' do=not wish to be limited thereto since it is only illustrative and various changes in design,1constructionand combination of parts may bemade without departing from the splrit of my invention as defined in the ap pended claims.

I claim 5-- i v 1. The combination with a hoisting crane trolley having a load carrying device, means .for raising-andlowering said device, and

electric power means for operating said first named means, of a limit'switch for breaking the forward operating circuit to said electricpower means to control the upward movementrofsaid load carrying device, and

flexible means adapted to be tripped by said load carrying device for operatin said switch, said last named means being adapted may be substituted for the esa-see to permit an appreciable upward overrun of said load carry device after said means has been tripped.

2. T he combination with a hoisting crane trolley having a bucket, means for raising and lowering said bucket, and electric power means for operating said first named means, of a rotary limit switch for breaking the forward operating circuit to said electric power means, a sheave wheel mounted on, and adapted to actuate said switch, a cable member secured to said sheave wheel and trained around other sheave wheels so as to extend across the path of travel of said bucket, said bucket being adapted to engage and trip said cable when it reaches a predetermined position thereby rotating said sheave wheel on said switch and breaking the circuit to said electriepower means.

, 3. The combination with a hoisting crane trolley having a bucket, means for raising and lowering said bucket, and electric power means for operating said first named means, of a rotary limit switch for breaking the forward operating circuit to said electric power means, a sheave wheel mounted on, and adapted to actuate said switch, a cable member secured to said sheave wheel and trained around other sheave wheels so as to extend across the path of travel of said bucket, said bucket being adapted to engage and trip said cable when it reaches a pre determined position thereb rotating said sheave wheel on said switcli and breaking the circuit to said electric power means, counterweights on said cable, and one of said counterweights being adapted to exert a ull on said cable to reset said switch when said bucket is lowered beyond its tripping position.

l. The combination with a hoisting crane trolley having a bucket, means for raising and lowering said bucket, and electric power means for operating said first named means, of a rotary limit switch for breaking the forward operating circuit to said electric power means, a sheave wheel mounted on and adapted to actuate said switch, a cable member secured adjacent its one end to said sheave wheel, the short end hanging from said sheave and the long end being trained around other sheave wheels so as to extend across the path of travel oi said bucket, counter-weights secured to the terminals of said cable, the counterweight on said short ed to return said end of said cable being of considerably less weight than the counterweight on said long end, means for supporting said weights, said bucket being adapted to engage said cable and move it upwardly so as to first raise said light weight and rotate said sheave wheel on said switch, thereby actuating said switch to break the circuit to said electric power means and to then raise, said heavy weight, and said weights being adaptcable and switch to normal closed position when said bucket is lowered.

5. In a crane hoisting apparatus a crane trolley, a bucket mounted for vertical move ment relative to said crane trolley, electrically operated means for raising and lowering said bucket, a rotary limit switch mounted on said trolley adapted to break the lifting circuit to said electrically operated means for raising and lowering the bucket, a sheave wheel mounted on and adapted to actuate said switch, an arched fender on said bucket, and means adapted to be tripped by said fender when said bucket is raised to a predetermined position for actuating said switch to break the lifting circuit to said electrically operated means, said last named means comprising a cable secured adjacent its one end to said sheave wheel, said cable having its short end hanging free from said sheave wheeland having a light counterweight secured thereto, sheaves supported on brackets extending below said trolley and spaced on each side of the path of travel of said bucket, the other and long end of said cable being trained over said last named sheaves so as to extend across the path of travel of said bucket, a counterweight of considerably greater weight than said first named counterweight secured to said long end of said cable, supports upon which said weights are adapted to rest when in their lower normal osition, said fender on said bucket being a apt-ed to engage and raise said cable when said bucket is raised beyond a predetermined position thereby rotating said sheave wheel on said switch,

and actuating said switch, and said counterweights being adapted to return said cable and switch to normal closed position when said bucket is lowered.

, In testimony whereof, I have hereunto signed my name.

SAML ARNOLD, 3D. 

